Friday 30 July 2010 19.05 EDT
First published on Friday 30 July 2010 19.05 EDT

For the men of Bravo Company, Fifth Marine Division, boredom and fear are almost as daunting a prospect as the guns of the North Vietnamese Army (NVA). Second Lieutenant Waino Mellas, just 19 and recently dropped in the jungle on the Laos border, finds his days "filled with nerve-racking tedium": "patrols and nighttime listening posts, the stupefying work of laying barbed wire, hacking out fields of fire with K-bars, digging holes, improving positions, eating, shitting, drinking, nodding off, trying to stay awake. Still, it beat humping."

Humping is marching, of which the men of Bravo Company also do a great deal. The form of Matterhorn, Karl Marlantes's first novel, is purposely structured on the typical soldier's divided experience. In the first of two equal parts, the reader slogs along with the men through numbing preparations for a plan to retake the mountain they have named Matterhorn. They held the position earlier, then abandoned it, only to see their own bunkers occupied advantageously by the NVA. The American commanding officers order one assault after another, and the second half of the story is taken up with the battles, which are brilliantly, sickeningly described. Modern American literature is rich in writing about war – from The Naked and the Dead by Norman Mailer through Tobias Wolff's wonderful memoir of his Vietnam duty, In Pharaoh's Army, to the recent poems about Iraq by Brian Turner – but nothing comes to mind to compare with the close-up evocations of combat in Matterhorn.

Marlantes, a richly decorated Vietnam veteran, is said to have spent 30 years on the novel, while working as a business consultant. The original typescript was more than twice the length of the finished book, which is probably still too long. A slow build-up is generally welcome in fiction, but Marlantes is not an experienced enough writer to keep the reader interested through 300 pages of dull routine, comradely joshing – "Do unto others before they do you. That's the fucking Golden Rule out here, Jack" – and edgy testing of authority. It is sometimes difficult to follow the action through forests of jargon and initials (DMZ, KP, LZ, RPG and so on – the glossary covers 30 pages). His numerous characters are insufficiently differentiated, and when their minds are not on the task that lies ahead, their emotions turn trite: "Slowly, with each breath, his anger grew: at the cliff, the bullshit, the hunger, the war, everything." There are echoes of the Hemingway of A Farewell to Arms in Mellas's tantrums: "He cursed the diplomats . . . He cursed the South Vietnamese . . . He cursed the people back home . . . Then he cursed God."

But Marlantes trumps Hemingway in one essential respect: he experienced the heat of battle (Hemingway drove an ambulance in the first world war) and the aftershocks are vividly present in his narrative. Curses against God are futile once the attack is under way. No God sensitive to curses would have landed them here.

"A stunned NVA soldier struggled to turn the machine gun on Goodwin but couldn't move fast enough. Goodwin, like a panther making a kill, was on top of him, firing his M-16. The remaining NVA in nearby gun pits stood up, weaponless, eyes filled with terror, and raised their hands . . . Mellas, still standing on the dead boy's body, slumped his head forward and rested his bloody, stinging face on the cool clay . . . 'We won', Jackson said." In common with warriors through the ages, the men of Bravo Company respect their enemies. The NVA know what they are fighting for – their country – but what of the Marines? There is scarcely a mention of US patriotism or any other national cause. Courage is pledged to one another. Hatred is reserved for their own commanding officers.

The main sub-theme of Matterhorn (it can't be called a subplot, since the novel doesn't have a main one) is race relations. The action is set in 1969, one year after the assassination of Martin Luther King, when the tone of civil rights protests had become more strident. "The nigras are up in arms with this black power crap," the colonel reflects, as he "carefully measured out just a little more whiskey". It's not just him – the good guys are also having problems adjusting to the evolving consciousness of the African American soldier. All-black cliques, the whites complain, disrupt company spirit. One black private claims to have relentless headaches and wants to go home. Doesn't everybody? Accusations of malingering (well-founded, as it turns out) have a familiar ring of racism to sensitive black ears. Mellas is portrayed as the voice of reason in this area (he is, after all, the main representative of his creator) but he is forced to face his own prejudices by the admired squad leader, Jackson.

Matterhorn is a story of men without women. When Mellas thinks of the girl he left behind in Virginia, Marlantes's prose becomes fluttery, as it does when Mellas, suffering an eye injury, is cared for by a nurse on board a medical ship. "They're sending you back to the bush," she says. "It's like I do my job well, and the result is sending you back to combat." In the inevitable movie, they might arrange it differently, just as the battle scenes are likely to seem studio-fabricated, inspiring a more familiar type of horror. Marlantes has demonstrated the supremacy of the written word. The tedious ascent of Matterhorn might seem drawn out to some readers, but they should savour each moment, before the shooting starts.

James Campbell's Talking at the Gates: A Life of James Baldwin is published by Faber.